1. Field of the Invention
The present invention relates to a turn behavior control of vehicles, and more particularly, to a driftout control of vehicles.
2. Description of the Prior Art
As a turn behavior control of vehicles, it is known to control the driftout of a vehicle by applying an unbalanced braking force or a traction force to some selected wheel or wheels of the vehicle, so as thereby to generate a yaw moment in the vehicle around the center of gravity thereof in the direction of assisting the turning of the vehicle. On the other hand, in the case of a four wheel steered vehicle, it is known that a sharp turn with no driftout is available by the rear wheels being steered in a direction opposite to that in which the front wheels are steered. The above two principles of controlling the driftout of vehicles can be combined when the vehicle is a four wheel steered vehicle. Indeed, it is proposed in Japanese Patent Laid-open Publication 4-81351 to control the driftout of a four wheel steered vehicle by a combination of a brake control and a rear wheel steering, wherein the rear wheels are steered in a direction opposite to that in which the front wheels are steered when the brake system is operated to generate a turn assist yaw moment in the vehicle for suppressing the driftout of the vehicle.
However, the essential problem residing in the driftout of the vehicle is that the wheels of the vehicle can no longer generate a centripetal side force required to support the centrifugal force acting at the vehicle during a turn by the frictional contact thereof with the road surface under the given conditions with regard to the slip angle and the vertical load.